1. Field of the Invention
The present inventions relate to an inspection system for glass sheet material including coated and non-coated glass.
2. Description of the Related Art
During the manufacture of optically transparent sheets, optical defects and deviations may be produced that render the transparent material imperfect. Optical imperfections are of special concern in glass and plastic sheet applications where optical defects are unacceptable from a quality control standpoint. Optical quality defects include surface imperfections, inclusions and inconsistencies in light transmission or reflection. Scratches, digs, coating anomalies, seeds, stones, chips, particles, tin residue, ripples, distortion, and grind lines are common categories of optical quality defects.
The optical quality of flat glass can be determined through the use a digital imaging device arranged to inspect the glass. This inspection could be done using illumination that reflects off the glass or transmits through the glass. The focus of the digital imaging device is on the glass sheet and the camera generates signals revealing the quality of the glass.
There are problems associated with the inspection of large area substrate such as glass or acrylic for window manufacture. High resolution imaging of discrete defects necessitates multiple cameras and lenses. Multiple imaging devices are typically arranged in series across the width of the substrate, as the substrate traverses a window processing line.
The linear arrangement of multiple cameras necessitated by large substrates makes the lighting of the substrate less than ideal. Uniform and omnidirectional lighting for one camera leads to optical interference with neighboring cameras.
The present invention addresses the fundamental limitations inherent in automated inspection systems for large-area substrate requiring multiple imaging devices arranged in series.
The illumination system used in this new and novel invention produces high contrast images of all types of defects, including very low contrast or very faint defects, and allows detection of a wide variety of defects at high velocity of glass movement.